Preparation method of positive electrode material for lithium-sulfur battery

Abstract

The invention belongs to the field of material chemistry and relates to a preparation method of a positive electrode material for a lithium-sulfur battery. According to the method, a composite material of which the effective loading amount of sulfur is significantly increased and the "shuttle effect" of polysulfides is reduced is obtained through three steps of preparing a graphene oxide aqueous solution, preparing a foamed graphene / carbon nanotube composite material and preparing a sulfur / foamed graphene / carbon nanotube composite positive electrode material. The material is used as a positiveelectrode material for a lithium battery, so that volume expansion of the lithium-sulfur battery can be effectively reduced, the electrochemical stability of the battery is improved, the first discharge capacity can reach 1529mAh / g and the discharge capacity is still 859mAh / g after 200 charge-discharge cycles.

Description

technical field [0001] The invention belongs to the field of material chemistry, and relates to a preparation method of a lithium-sulfur battery positive electrode material, more specifically, to a preparation method of a foamed graphene / carbon nanotube composite material. Background technique [0002] With the continuous development of science and technology, the continuous improvement of industrial level, people's demand for energy is increasing day by day, fossil energy reserves have been increasingly depleted under the continuous development of people, and the development of new energy has become a problem that people have to face up to. Optimizing the energy structure, vigorously The development of new energy and renewable energy is an important task in my country's current energy work. Secondary batteries represented by lithium-ion batteries have become the focus of attention, especially with the continuous development of electric vehicles and portable electronic device...

AI Technical Summary

Problems solved by technology

[0004] 1. Elemental sulfur is an electronic and ion insulator, and its conductivity at room temperature is only 5*10 -30 S / cm, as a positive electrode material, the electrochemical activity is not high

[0005] 2. The density of elemental sulfur and charge and discharge product sulfide is different, and serious volume expansion will occur, and the volume expansion rate is about 76%.

And repeated volume changes during charging and discharging will eventually destroy the physical structure of the battery and cause the entire battery system to collapse

[0006] 3. The unique shuttle effect of lithium-sulfur batteries, that is, the polysulfides generated during the charging and discharging process of the battery shuttle back and forth between the positive and negative electrodes, causing the battery to self-discharge.

The shuttle effect of lithium-sulfur batteries will affect the normal battery charge and discharge process, reduce the specific capacity of the battery and the cycle stability of the battery

[0007] 4. The polysulfides generated during the charging and discharging of lithium-sulfur batteries will dissolve in the currently used electrolyte solution, resulting in the loss of active materials of the positive electrode material and reducing the overall electrochemical performance of the battery

There are many reports on the application of graphene in lithium-sulfur batteries, but the application of graphene in lithium-sulfur batteries in the prior art has improved the performance of lithium-sulfur batteries to a certain extent, but the common defect is: the positive electrode The effective loading of sulfur in the material is low, the "shuttle effect" of polysulfides is obvious, the volume expansion effect of lithium-sulfur batteries is significant, and the electrochemical performance of the batteries is unstable

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